Filter cassette



FIG. 1 is a right side view of a filter cassette showing the design where the left side view is a mirror image of this view;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a front view thereof; and,

FIG. 5 is a rear view thereof.

The broken line showing of is included for the purpose of illustrating environment and forms no part of the claimed design. 

The ornamental design for a filter cassette, as shown and described. 